The invention concerns the detection of persons or objects fitted with portable electronic units, or electronic tickets, particularly including means for receiving electromagnetic signals, these persons or objects being capable of entering or leaving a delimited space, via at least one entry-exit.
The system includes in particular a detection device associated with this delimited space and including electromagnetic signal transmission means.
The present invention concerns more particularly such a passage detection system wherein the transmission means of the detection device associated with the delimited space are arranged to transmit different first and second electromagnetic signals in respectively first and second communication regions separated spatially from each other and partially overlapping each other, these first and second regions each covering an entry-exit zone defined by the entry-exit to the delimited space.
A system for detecting persons or objects having the aforementioned features is disclosed particularly in International Patent Application No. WO 01/03057 also in the name of the Applicant, which is incorporated herein by reference. One could also refer to European Patent Application No. 00204758.8 of 29 Dec. 2000 entitled “Systéme de détection du passage d'un individu ou objet par une entrée-sortie á un espace délimité >> also in the name of the Applicant.
The use of two partially superposed electromagnetic fields advantageously allows detection of the direction of passage, through the entry-exit, of a person or an object fitted with a portable electronic unit. For this purpose, there are provided, within the scope of the present invention, means for detecting the direction of passage of a person or an object as a function of the reception, by the electronic unit, of first and second electromagnetic signals respectively transmitted in the first and second communication regions.
FIG. 1 schematically illustrates an implementation example of an aforementioned detection system. Persons or objects are capable of entering or leaving a delimited space 2 (for example a means of public transport such as a passenger carriage or bus) through at least one entry-exit, indicated by the reference 4. As already mentioned, a detection device is associated with delimited space 2 and includes, in particular, transmission means 8. These transmission means 8 include an electronic circuit 10 connected to a pair of antennae 12, 13 arranged at entry-exit 4. Antennae 12, 13 transmit respectively, preferably at a relatively low frequency (of the order of a hundred kHz), a first and a second electromagnetic signal, designated “a” and “b” in the following description, in respectively first and second communication regions A and B shown schematically in FIG. 1. These communication regions A and B cover an entry-exit zone 32 to delimited space 2 defined by entry-exit 4.
Communication regions A and B are at least partially separated from each other and have a common zone or overlapping zone indicated by the hatched zone AB. In practice, this overlapping zone AB can be significant in terms of surface area and, in particular, be larger than the non-superposed regions of the two communication zones A, B. When a person or an object fitted with a portable electronic unit, designated 40 in FIG. 1, passes through entry-exit 4, as schematically illustrated by arrow 34, or passes into zone 32, the portable electronic unit thus successively penetrates into and/or the other of communication regions A, B. Portable electronic unit 40 with which each person or object is fitted, thus picks up a succession of the first and second electromagnetic signals “a” and “b” transmitted by antenna 12, 13. The order and succession of electromagnetic signals received by portable electronic unit 40 allows the direction of passage of the person or object through entry-exit 4 to be identified.
The robustness of this detection of the direction of passage is greatly dependent upon the extent of overlapping zone AB between the two communication regions A, B. Inside this overlapping zone AB, electronic unit 40 receives both the first electromagnetic signal “a” and the second electromagnetic signal “b” respectively transmitted by antennae 12 and 13. The direction of passage of electronic unit 40 in overlapping zone AB cannot therefore be determined based solely on identification of the received electromagnetic signals. Taking account of the real spatial arrangement of communication regions A, B and/or the speed of movement of electronic unit 40 through entry-exit 4, there is a relatively high probability that the portable electronic unit will be directly or too quickly in overlapping zone AB, such that the actual direction of passage of portable electronic unit 40 cannot be properly detected.